The present invention relates generally to the field of micro-LCD (liquid crystal display) projectors for displaying color images on a screen. More specifically, the present invention relates to a light engine for projecting a LCD display image on a front or rear screen.
Micro Liquid crystal display projectors project a scaled image of an image on a micro-LCD to a screen. Micro-LCD projectors generally include four major components: an illumination source, a light engine, micro liquid-crystal-on-silicon (LCOS) valves, and a projection lens.
In operation, the illumination source provides a high intensity polychromatic or white light through the light engine to the LCOS valves. The LCOS valves incorporate the LCD image into the light and send the light back through the light engine, which directs the light through the projection lens onto a projection screen or surface.
Micro-LCD projectors have the advantage of creating large images for viewing. However, Micro-LCD projectors have traditionally compromised image clarity in favor of image size. Additionally, Micro-LCD projectors have historically been very expensive.
With increased performance, better picture quality, and lower prices, micro-LCD projector use has been increasing in both the consumer market and the business market. Given the expanding use, it is likely that it will be desirable to use a micro-LCD projector in a wide variety of applications. One possible application for a micro LCD projector may be to implement a cockpit display for an airplane.
However, current micro-LCD projectors are required to have a minimum size to house conventional components. The relatively large minimum size is prohibitive for many prospective applications. An airplane cockpit is one example of an application where a compact micro-LCD projector would be desirable.
The light engine is one component, among others, where efficiencies may be gained in both increasing the quality of the image that is projected and reducing the size of the projector. By decreasing the size of the light engine, it is possible to decrease required minimum size of the micro-LCD projector.
Accordingly, there is a need for a compact light engine that facilitates the construction of a compact micro-LCD projector. There is also a need for a compact light engine that can provide the size efficiencies while maintaining, or even increasing, image quality.
An exemplary embodiment of the invention relates to a micro liquid crystal display projector comprising a light source emitting a light beam, a light engine, and a projection lens. The light engine includes a polarizing beam splitter for receiving the light beam from the light source, wherein the polarizing beam splitter orthogonally reflects a light beam containing multiple colors and passes a first light beam containing a single color, a dichroic prism that receives the light beam containing multiple colors, reflects a second light beam containing a single color, and passes a third light beam containing a single color, and reflective liquid crystal displays associated with each of the first, second, and third light beams containing a single color for receiving, modulating, and reflecting modulated first, second, and third light beams containing a single color for recombination and projection through the projection lens.
Another exemplary embodiment of the invention relates to a micro liquid crystal display projector including a light source emitting an s-polarized multi-colored light beam, a light engine, and a projection lens. The light engine includes a color manipulation filter pair that receives the s-polarized multi-colored light beam and outputs an s-polarized light beam containing two colors distilled from the multi-colored light beam and a p-polarized light beam containing a single color. The light engine also includes a polarizing beam splitter to reflect the s-polarized light beam containing two colors distilled from the multi-colored light beam and to pass the single colored p-polarized light beam. Further, the light engine includes a dichroic prism unit for receiving the s-polarized light beam containing two colors distilled from the multi-colored light beam, the dichroic prism unit including a colored gradient dichroic mirror positioned at a 45 degree angle to the s-polarized light beam containing two colors to separate the s-polarized light beam containing two colors into first and second s-polarized light beams containing a single color. Further still, the light engine includes a cubic glass for receiving and passing the single p-polarized light beam containing a single color. Yet further still, the light engine includes a half wave retarder for receiving the single p-polarized light beam from the cubic glass and converting the single p-polarized light beam into a third s-polarized light beam containing a single color. Yet still further, the light engine includes a first, second and third reflective liquid crystal displays associated with each s-polarized light beam containing a single color for receiving the s-polarized light beam containing a single color, modulating the light beam and reflecting first, second, and third modulated light beams containing a single color respectively for transmission back to the polarizing beam splitter for polarizing selection and recombination, wherein the third modulated light beam containing a signal color passes through the half wave retarder to become a further modulated light beam. Still yet further still, the light engine includes a second color filter pair for receiving a recombined light beam from the polarizing beam splitter containing first and second modulated p-polarized light beams containing a single color and the modulated s-polarized light beam, wherein the second color filter pair convert the modulated s-polarized light beam into a p-polarized state to create a single polarized light beam that is provided as output to the projection lens.
Yet another exemplary embodiment of the invention relates to a method for projecting an LCD image on a screen through a projection lens. The method includes providing a light beam emitted from a light source, passing the light beam through a polarizing beam splitter to produce a first light beam containing a single color and a light beam containing multiple colors, passing the light beam containing multiple colors through a dichroic prism to produce second and third light beams containing a single color, passing the first, second, and third light beams containing a single color to associated first, second, and third reflective liquid crystal displays for modulation and reflection, and recombining the modulated first, second, and third light beams for projection though the projection lens.